i am just trying basic only but not able to do...
Create a file named "logstash-simple.conf" and save it in the same directory as Logstash.
Then, run logstash and specify the configuration file with the -f flag.

bin/logstash -f logstash-simple.conf

i am not able to see anything

bin/logstash-2.0.0-1 -f logstash-simple.conf
-bash: bin/logstash-2.0.0-1: No such file or directory

in /bin directory i have created a folder with version of logstash-2.0.0-1 and created a .conf file with basic code as given in URL
input { stdin { } }
output {
elasticsearch { hosts => ["localhost:9200"] }
stdout { codec => rubydebug }
}

so as per document i am trying to execute the command "bin/logstash -f logstash-simple.conf"

Ok you need to run bin/logstash -f /path/to/logstash-simple.conf. The bin/logstash part is simply a convention or short hand for "invoke the logstash binary". If you saved the logstash directory under /bin, i suspect that your invocation should be /bin/logstash-2.0.0.1/bin/logstash -f /path/to/logstash-simple.conf. To confirm:

What is your absolute path to the logstash binary? and to logstash-simple.conf?